A “quick” step backwards

Blanched Formula

• Good way to calculate r if the means and standard deviations are already provided.

• It is very time consuming to calculate these statistics if they are not already provided

• If means and standard deviations are not given, use the raw-score formula

Raw-Score Formula

r =

Step 1: Set up table

SmileY

TalkX

Y2 X2 XY

Jerry 9 5Elan 2 1George 5 3Newman 4 4Kramer 3 2

Step 2: Square Y

SmileY

TalkX

Y2 X2 XY

Jerry 9 5 81Elan 2 1 4George 5 3 25Newman 4 4 16Kramer 3 2 9

Step 3: Square X

Smile Y

Talk X

Y2 X2 XY

Jerry 9 5 81 25 Elan 2 1 4 1 George 5 3 25 9 Newman 4 4 16 16 Kramer 3 2 9 4

Step 4: Multiply XY

Smile Y

Talk X

Y2 X2 XY

Jerry 9 5 81 25 45 Elan 2 1 4 1 2 George 5 3 25 9 15 Newman 4 4 16 16 16 Kramer 3 2 9 4 6

Step 5: Sum

SmileY

TalkX

Y2 X2 XY

Jerry 9 5 81 25 45Elan 2 1 4 1 2George 5 3 25 9 15Newman 4 4 16 16 16Kramer 3 2 9 4 6

23 15 135 55 84

Step 6: Plug in values

r =

Y = 23 Y2 = 135

X =15 X2 = 55

XY = 84 N = 5

Step 6: Plug in values

r =15

15

Y = 23 Y2 = 135

X =15 X2 = 55

XY = 84 N = 5

Step 6: Plug in values

r =23

23

Y = 23 Y2 = 135

X =15 X2 = 55

XY = 84 N = 5

15

15

Step 6: Plug in values

r =84

Y = 23 Y2 = 135

X =15 X2 = 55

XY = 84 N = 5

23

23

15

15

Step 6: Plug in values

r =84

55

Y = 23 Y2 = 135

X =15 X2 = 55

XY = 84 N = 5

23

23

15

15

Step 6: Plug in values

r =84

135

Y = 23 Y2 = 135

X =15 X2 = 55

XY = 84 N = 5

55

23

23

15

15

Step 6: Plug in values

r =84(5)

(5) (5)

Y = 23 Y2 = 135

X =15 X2 = 55

XY = 84 N = 5

13555

23

23

15

15

Step 7: Solve!

r =84(5)

(5) (5)

Y = 23 Y2 = 135

X =15 X2 = 55

XY = 84 N = 5

13555

23

23

15

15

Step 7: Solve!

r =23 225

84(5)

(5) (5)225 529

Y = 23 Y2 = 135

X =15 X2 = 55

XY = 84 N = 5

13555

2315

Step 7: Solve!

r =23

23

15

225

23

275 675

420 345

Y = 23 Y2 = 135

X =15 X2 = 55

XY = 84 N = 5

225 529

Step 7: Solve!

r =23

23

15

225

23420 345

50 146

Y = 23 Y2 = 135

X =15 X2 = 55

XY = 84 N = 5

Step 7: Solve!

r =23

23

15

225

23

146 507300

75

Y = 23 Y2 = 135

X =15 X2 = 55

XY = 84 N = 5

Step 7: Solve!

r =23

23

15

225

23

146 507300

75

85.44

Y = 23 Y2 = 135

X =15 X2 = 55

XY = 84 N = 5

Step 7: Solve!

.88 =23

23

15

225

23

146 507300

75

85.44

Y = 23 Y2 = 135

X =15 X2 = 55

XY = 84 N = 5

Practice

AlcoholX

Nose TouchesY

Norm 6 5

Cliff 8 1

Sam 4 4

Woody 2 9

Practice

AlchX

NoseY

X2 Y2 XY

Norm 6 5Cliff 8 1Sam 4 4Woody 2 9

Practice

AlchX

NoseY

X2 Y2 XY

Norm 6 5 36 25 30Cliff 8 1 64 1 8Sam 4 4 16 16 16Woody 2 9 4 81 18

20 19 120 123 72

Practice

r =

X = 20 X2 = 120

Y =19 Y2 = 123

XY = 72 N = 4

20

20

19

19

72

120 123

(4)

(4) (4)

Practice

r =

X = 20 X2 = 120

Y =19 Y2 = 123

XY = 72 N = 4

20

20

19

19120 123(4) (4)

-92

Practice

r =

X = 20 X2 = 120

Y =19 Y2 = 123

XY = 72 N = 4

20 19-92

80 131

Practice

-.90 =

X = 20 X2 = 120

Y =19 Y2 = 123

XY = 72 N = 4

20 19-92

80 131102.37

Practice

• Page 116 -- # 21

Practice• Interpret the following:

• 1) The correlation between vocational-interest scores at age 20 and at age 40 was .70.

• 2) Age and IQ is correlated -.16.

• 3) The correlation between IQ and family size is -.30.

• 4) The correlation between sexual promiscuity and dominance is .32.

• 5) In a sample of males happiness and height is correlated .11.

Practice

• Page 97 # 5